High speed signal comparison is widely used in many applications, i.e., high speed datacom receivers and high speed flash A/D converters. In those applications, the comparison is usually done by concatenating the pre-amplifier to amplify the input signal and the high-gain re-generated comparator to provide the final decision. The comparator speed is a function of both the signal swing and the comparator input common mode voltage.
Some prior art devices increase the pre-amplifier's gain at the cost of lowering the amplifier's speed. Other prior art devices increase the sizes of the amplifier and comparator to reduce the offset, but this burns more power.